JP7131286B2 - Image analysis type particle analyzer - Google Patents

Description

The present invention relates to an image analysis type particle analyzer.

As various particle analyzers for analyzing the properties of particles, image analysis type particle analyzers are known that perform image analysis on particle images obtained by photographing particles and analyze the particle properties based on the results of the image analysis (for example, See Patent Document 1). Generally, in an image analysis analyzer, a sample liquid in which sample particles are dispersed is caused to flow through a channel provided inside a flow cell, and the flow of the sample liquid is photographed by a camera to obtain a particle image.

By the way, the sharpness of the particle image is a factor that greatly affects the analysis results, and in order to obtain a clear particle image, it is important to focus the camera on the channel of the flow cell. Therefore, in general, a standard sample liquid in which standard sample particles for focusing are dispersed is passed through the channel of the flow cell, and the user manually adjusts the focus of the camera so that the sample particles in the standard sample liquid are clearly captured. things are done.

JP-A-8-136439

However, manually adjusting the focus of the camera is a cumbersome task and also leads to a decrease in the accuracy of analysis results.
Therefore, for example, if a target marker for camera focusing is provided on the surface of the flow cell and the camera is automatically focused on this target marker, the user's effort for focusing can be reduced.
However, in this configuration, the camera is focused on the surface of the flow cell rather than on the channels internal to the flow cell. For this reason, the definition of the particle image is inferior to that in the case of focusing on the channel of the flow cell. In addition, depending on the distance from the surface of the flow cell to the channel, the depth of the channel may not fit within the depth of field of the camera, resulting in a blurred particle image. Furthermore, not all flow cells have the same distance from the surface to the channel, and it is difficult to uniformly and accurately focus the surface of the flow cell on the channel.

SUMMARY OF THE INVENTION An object of the present invention is to provide an image analysis type particle analyzer capable of accurately focusing on the flow channel of the flow cell.

A first invention comprises a flow cell in which a sample liquid flow path in which sample particles are dispersed is installed, a light source device for irradiating the flow path with measurement light, and a camera for photographing the flow of the sample liquid in the flow cell. , wherein an image analysis type particle analyzer for analyzing the properties of the sample particles based on the image of the sample particles taken by the camera, comprising a focus adjustment unit for adjusting the focus of the camera, the flow cell has a base plate body having flow channel grooves on its surface, and a cover plate body joined to the surface of the base plate body in a surface-to-surface contact state to close the flow channel grooves and form the flow channels. A focus target for focusing is provided on the surface of the base plate or the surface of the cover plate on the joint side, and the focus adjustment section adjusts the camera based on the focus target. The focus target comprises a focus target groove, which is a groove formed on the surface of the base plate or the surface of the cover plate on the bonding side, and the focus target groove is formed on the opening end face. a side surface that slopes from an edge to a bottom, the side surface producing a dark line in a captured image of the focal target, and the focus adjustment unit adjusts a position of a sharp portion in the dark line, and/or The focus of the camera is adjusted based on the position of the blurred area, and the flow cell is provided with an air passage communicating between the focus target groove and the outside .

A second invention is characterized in that, in the first invention, the focal target groove has a V-shaped cross section .

In a third invention based on the first or second invention, the focus adjustment unit adjusts the focal point of the camera based on the dark line and the depth from the opening end face of the flow channel. is aligned with a position that is half the depth of the channel groove in the depth direction of the channel groove from the open end face of the channel groove .

According to the first invention, since the focus target for focusing is provided on the surface of the base plate or on the surface of the cover plate on the bonding side, regardless of the thickness of the cover plate, the camera can can be accurately focused on the surface of the base plate. As a result, the open end face of the channel groove (that is, one surface of the channel) formed on the surface of the base plate is accurately focused.
Also, according to the first invention, the camera can be focused accurately on the open end face of the focus target groove, that is, on the surface of the base plate.
Further, according to the first invention, even if the air inside the focal target groove expands, the expanded air is discharged to the outside through the air passage. Therefore, deformation of the cross-sectional shape of the flow path is prevented.
According to the second invention, it is possible to reduce the area unnecessary for focus determination in the dark line, and narrow the opening width of the focus target groove.
According to the third invention, the entire depth direction of the channel groove (channel) can be reliably contained within the depth of field of the camera.

1 is a diagram schematically showing the configuration of an image analysis type particle analyzer according to an embodiment of the present invention; FIG. It is a figure which shows the structure of a flow cell, (A) is a top view, (B) is a side view which looked at the inlet. 3 is a cross-sectional view taken along line III-III of FIG. 2; FIG. FIG. 4 is an illustration of dark lines caused by focal target grooves; FIG. 4 is a diagram showing the relationship between the focus of the camera and the blurred and sharp portions of the dark line; FIG. 10 is a diagram showing a modification of the focal target groove according to the present invention; FIG. 4 is a diagram showing a modified example of the flow cell according to the present invention; FIG. 4 is a diagram showing another modification of the flow cell according to the present invention;

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram schematically showing the configuration of an image analysis type particle analyzer 1 according to this embodiment.
This image analysis type particle analyzer 1 performs image analysis on a particle image showing particles of a sample powder dispersed in a sample liquid, and analyzes the particle properties of the sample powder based on the results of the image analysis. . Sample powders are powders of industrial products such as pigments, cosmetic powders, toners, particulate catalysts, abrasives, powdered medicines, synthetic resin powders, and fine ceramic particles. Particle properties are typically particle shapes, and circle-equivalent diameters, circularity, aspect ratios, and the like are required.

The image analysis type particle analyzer 1 includes a flow cell 2, a sample liquid supply mechanism 4, an illumination unit 6, a camera 8, a focus mechanism 10, and a computer 12, as shown in FIG.
The flow cell 2 is an optically substantially transparent measurement container and has a substantially rectangular plate shape. An inlet 14A for introducing the sample liquid and an outlet 14B for discharging the sample liquid are formed in the upper end surface 2A and the lower end surface 2B of the flow cell 2, respectively. A flow path 16 leading to an outlet 14B is provided in a straight line.
The flow cell 2 of this embodiment is provided with a focus target 20 (see FIG. 3) for focusing, and the computer 12 automatically focuses the camera 8 based on the focus target 20 .

The sample liquid supply mechanism 4 is a mechanism that feeds a predetermined amount of sample liquid into the flow cell 2 at a time, and includes a liquid feed pump 22 .
In this embodiment, an introduction tube 26 extending from a sample liquid storage container 24 that stores the sample liquid to be measured is connected to the introduction port 14A of the flow cell 2 . One end of a discharge pipe 28 is connected to the discharge port 14B, and the other end of the discharge pipe 28 is connected to the suction side of the liquid feed pump 22 . By operating the liquid-sending pump 22, the sample liquid in the sample liquid storage container 24 flows from the inlet 14A into the channel 16 of the flow cell 2, passes through the channel 16, and is discharged from the outlet 14B. A waste liquid pipe 30 is connected to the discharge side of the liquid feed pump 22 , and the sample liquid discharged by the liquid feed pump 22 is collected in a waste liquid tank 32 through the waste liquid pipe 30 . Needless to say, the liquid-sending pump 22 may be provided on the introduction pipe 26 side.

The illumination unit 6 includes a light source device 6A that irradiates the flow cell 2 with measurement light 34 . The light source device 6A of the present embodiment irradiates the measurement light 34 of substantially parallel light from a direction substantially orthogonal to the flow channel 16 of the flow cell 2 . The light source device 6A includes a light source having a light emitting element such as an LED light source or a laser light source, and a collimating optical system for collimating light emitted from the light source. The light source device 6A may include a planar light source that emits light planarly, such as a COB type (chip-on-board type) LED.

The camera 8 is arranged at a position facing the illumination unit 6 with the flow cell 2 interposed therebetween, and is a photographing device for photographing a portion of the flow cell 2 irradiated with the measurement light 34 . The camera 8 of this embodiment includes an imaging device 36 such as a CCD or CMOS, which is an imaging sensor, and a telecentric microscope 38 . The telecentric microscope 38 is a telecentric optical system that forms an image of the irradiation site in the flow cell 2 on the imaging surface 36A of the imaging device 36, and includes a telecentric lens 40 arranged opposite to the flow cell 2.

The focus mechanism 10 is a mechanism for varying the focal point of the telecentric microscope 38 and includes a lens drive mechanism 42 . The lens drive mechanism 42 is a mechanism that changes the focus of the camera 8 by linearly moving the telecentric lens 40 along the optical axis A of the telecentric optical system under the control of the computer 12 .

The computer 12 has a function of automatically adjusting the focus of the camera 8 (telecentric microscope 38) based on the photographed image 46 (FIG. 5) of the focus target 20 of the flow cell 2. An adjustment unit 50 is provided.
More specifically, the autofocus adjustment section 50 includes a captured image analysis section 52 and a camera control section 54 .
The captured image analysis unit 52 captures the captured image 46 of the camera 8 and determines the shift between the focus of the camera 8 and the focus target 20 based on the captured state of the focus target 20 captured in the captured image 46 . The camera control unit 54 controls the lens drive mechanism 42 so that the telecentric lens 40 moves to a position that eliminates the defocus. This brings the camera 8 into focus on the focal target 20 .

The computer 12 includes a processor such as a CPU or MPU, a memory device such as a ROM or RAM, a storage device such as an HDD or SSD, and an interface circuit for connecting the camera 8 or the like. Alternatively, various functions shown in FIG. 1 are implemented by executing computer programs stored in the storage device.

In addition to the components shown in FIG. 1, the image analysis type particle analyzer 1 includes an analysis device for analyzing the properties of sample particles based on a particle image showing the sample particles. Of course, the computer 12 may realize the function of this analysis device.

Next, the configuration of the flow cell 2 will be described in detail.
2A and 2B are diagrams showing the configuration of the flow cell 2, FIG. 2A being a plan view and FIG. 2B being a side view of the inlet 14A. FIG. 3 is a cross-sectional view taken along line III--III in FIG.
As shown in FIG. 2(B), the flow cell 2 of this embodiment has a base plate 60 and a cover plate 61 which have substantially the same size and shape in a plan view. 61 are joined by lamination in a state of surface contact. The base plate 60 and the cover plate 61 are made of an appropriate material (glass material in this embodiment) that is transparent and resistant to attack by the sample liquid.

As shown in FIG. 3, the surface 60A of the base plate 60 is formed with one channel groove 63 and two focus target grooves 65. As shown in FIG.
As shown in FIG. 2A, the flow channel 63 extends linearly from the upper end surface 2A to the lower end surface 2B of the flow cell 2, and the open end surface 63A thereof is closed by the cover plate 61 so that the flow cell 2 The flow path 16 described above is formed in the interior of the . The opening end face 63A of the flow channel groove 63 and the surface 60A of the base plate 60 are flush with each other, and one surface of the flow channel 16 is formed by closing the opening end face 63A.
In the present embodiment, as shown in FIG. 2B, the channel groove 63 is formed in a substantially rectangular cross-sectional view with a predetermined width W (eg, 1 mm) and a predetermined depth Da (eg, 120 μm). there is The depth Da is at least smaller than the width W, and the channel 16 is formed flat. Further, in the present embodiment, the camera 8 (more precisely, the telecentric microscope 38) has a depth of field that is at least the depth Da of the channel groove 63 (channel 16) or more, and the depth of the channel 16 The full range of directions is kept within the depth of field.

The focal target groove 65 is a groove having a depth Db (FIG. 3) that becomes the focal target 20. As shown in FIG. It is provided so as to extend These focal target grooves 65 are also closed by the cover plate 61 at their open end surfaces 65A in the same manner as the channel grooves 63 . The point that the opening end face 65A of the focal target groove 65 and the surface 60A of the base plate 60 are flush with each other is also the same as the channel groove 63 .

Here, since the air inside the focal target groove 65 expands during measurement and applies pressure to the joint surface between the base plate 60 and the cover plate 61, the cross-sectional shape of the channel 16 may be deformed. be. Therefore, in order to release this air pressure to the outside, the flow cell 2 is provided with one or a plurality of (a plurality in the illustrated example) air passages 68 extending from the focal target groove 65 to the outside, as shown in FIG. 2(A). ing. In this embodiment, the ventilation path 68 is formed by providing grooves in the surface 60A of the base plate 60, but it can be provided in an appropriate manner using an appropriate method for forming the ventilation path 68. FIG.

Now, the focal target groove 65 of this embodiment is formed by etching the surface 60A of the base plate 60, and as shown in FIG. It has a substantially U-shaped cross section. That is, the side surfaces 71A and 71B from the surface 60A of the base plate 60 to the bottom 70 of the focal target groove 65 form curved slopes. Therefore, when the camera 8 photographs the focal target groove 65 from the cover plate 61 side while the measurement light 34 is irradiated from the base plate 60 side, the focal target groove 65 is captured as shown in FIG. Sides 71 A, 71 B of 65 image focal target groove 65 as a dark line 75 , which serves as focal target 20 .

It is also conceivable to focus the camera 8 on the focus target 20 consisting of the dark line 75 using any suitable autofocus technique, but this has the following disadvantages. That is, since the focal target groove 65 has the depth Db, in the depth direction of the focal target groove 65, it is inaccurate which position the focus is on. It becomes unclear where the focus is in the direction.

Therefore, in the present embodiment, the camera 8 is focused on the open end surface 65A of the focal target groove 65, and the surface 60A of the base plate 60, which is one surface of the flow path 16, is focused on by the camera 8 as follows. I'm trying
That is, the side surfaces 71A and 71B of the focal target groove 65 are inclined from the edge 65A1 of the opening end surface 65A toward the bottom 70, so that the side surfaces 71A and 71B have a depth when viewed from the camera 8. Therefore, when the focus target groove 65 is photographed, the in-focus portions on the side surfaces 71A and 71B become sharp, and the out-of-focus portions become blurred. A sharp portion and a blurred portion appear depending on the position.

Specifically, when the camera 8 is focused on the open end face 65A of the focal target groove 65, as shown in FIG. A portion 80A on the near side) is blurred, and a portion 80B on the outside of the side surfaces 71A and 71B (that is, the side near the surface 60A of the base plate 60) becomes sharp.
Conversely, when the camera 8 is focused on the bottom 70 of the focal target groove 65, as shown in FIG. is generated, and the inner portion 80A becomes sharp.

Therefore, in the dark line 75 (more precisely, in the transverse direction of the dark line 75), the sharpest point is located in the outer portion 80B of the side surfaces 71A and 71B (in other words, the most blur occurs). is located in the inner portion 80A), the camera 8 is focused on the surface 60A of the base plate 60, that is, the opening end face 63A of the flow channel 63 is focused. The state can be accurately detected.

Therefore, when the computer 12 of the present embodiment executes processing for automatically focusing the camera 8 (automatic focusing processing), the captured image analysis unit 52 of the autofocus adjustment unit 50 performs the following based on the captured image 46: The sharpest point and/or the most blurred point in the dark line 75 is detected, and the sharpest point is located in the outer portion 80B of the dark line 75 and/or the most blurred point. It is determined that the focus of the camera 8 is on the surface 60A of the base plate 60 when the location is located in the inner portion 80A of the dark line 75 .
On the other hand, in other cases, the camera control unit 54 causes the autofocus adjustment unit 50 to position the sharpest point of the dark line 75 in the outer portion 80B of the dark line 75 and/or to cause the most blurring. The lens drive mechanism 42 is controlled to move the telecentric lens 40 so that the location is located in the inner portion 80A of the dark line 75 .
By such control of the autofocus adjustment unit 50, the focus of the camera 8 is adjusted to the open end surface 65A of the focal target groove 65, that is, the surface 60A of the base plate 60, and as a result, to the open end surface 63A of the flow channel groove 63. be done.

After that, the autofocus adjustment unit 50 causes the camera control unit 54 to move the focus of the camera 8 in the direction of the depth Da of the channel groove 63 by an amount corresponding to 1/2 of the depth Da from the opening end surface 63A, The camera 8 is focused on the center of the channel groove 63 (channel 16) in the depth direction, and the automatic focusing process ends.
By focusing the camera 8 on the center of the channel 16 in the depth direction in this manner, the entire depth of the channel 16 can be reliably contained within the depth of field of the camera 8 . As a result, the sample particles flowing through the flow path 16 can be clearly photographed, and the properties of the sample particles can be accurately analyzed.

Any image processing technique can be used as a method for the photographed image analysis unit 52 to detect a sharp portion or a blurred portion in the dark line 75 . For example, the photographed image analysis unit 52 obtains the contrast distribution in the transverse direction of the dark line 75, and designates a portion with relatively high contrast as a sharp portion, or a portion with relatively low contrast as a blurred portion. can be specified as

In this embodiment, the automatic focusing process by the computer 12 is performed at an appropriate timing such as after the flow cell 2 is set in the image analysis type particle analyzer 1, before measurement is started, or during measurement. In this automatic focusing process, the user may manually adjust the focus of the camera 8 while viewing the photographed image 46 displayed on the monitor device or the like by the computer 12 .

According to this embodiment, the following effects are obtained.

In the image analysis type particle analyzer 1 of this embodiment, the flow channel 63 forming the flow channel 16 is provided on the surface 60A of the base plate 60 of the flow cell 2, and the focusing is performed on the same surface 60A. A focus target 20 is provided, and the autofocus adjustment unit 50 adjusts the focus of the camera 8 based on this focus target 20 .
In this way, since the focus target 20 for focusing is provided on the surface 60A of the base plate 60, regardless of the thickness of the cover plate 61 of the flow cell 2, the focus of the camera 8 is on the base plate 60. can be precisely matched to the surface 60A of the Therefore, the opening end surface 63A (one surface of the flow path 16) of the flow path groove 63 formed in the surface 60A of the base plate 60 is accurately focused.

In the image analysis type particle analyzer 1 of this embodiment, the focal target 20 has a focal target groove 65 formed in the surface 60A of the base plate 60, and the focal target groove 65 extends from the open end face 65A to the bottom 70. It has sides 71A, 71B that tilt to produce a dark line 75 in the captured image 46 of the focal target 20 in question. Then, the autofocus adjustment unit 50 adjusts the focus of the camera based on the position of the sharp part and/or the part where the blur occurs in the dark line 75 .
As a result, the camera 8 can be focused accurately on the surface 60A of the base plate 60 which is flush with the opening end face 65A of the focus target groove 65. FIG.

In the image analysis type particle analyzer 1 of the present embodiment, the autofocus adjustment unit 50 adjusts the focal point of the camera 8 based on the dark line 75 and the depth Da from the opening end surface 63A of the flow channel 63 to the flow channel. 63 in the depth direction of the channel groove 63, and is aligned with a position that is half the depth Da of the channel groove 63. As shown in FIG.
Thereby, the entire depth direction of the flow path 16 can be reliably contained within the depth of field of the camera 8 .

In the image analysis type particle analyzer 1 of this embodiment, the flow cell 2 is provided with an air passage 68 that communicates the focal target groove 65 with the outside.
As a result, even if the air inside the focal target groove 65 expands during measurement, it is released to the outside through the air passage 68, so that the joint surface between the base plate 60 and the cover plate 61 is pressurized by the expanded air. The cross-sectional shape of the flow path 16 is not deformed.

The above-described embodiment is merely an example of one aspect of the present invention, and can be arbitrarily modified and applied without departing from the scope of the present invention.

In the above-described embodiment, the focal target groove 65 forming the focal target 20 has a U-shaped cross section, but the present invention is not limited to this. For example, as shown in FIG. 6, the focal target 120 may be formed by a focal target groove 165 having a V-shaped cross section. In the focal target groove 165 having a V-shaped cross section, the area occupied by the bottom 170 with respect to the opening width E is smaller than that of the focal target groove 65 having a U-shaped cross section. Along with this, in the dark line 75 as well, the ratio of the side surfaces 171A and 171B of the focal target groove 165 having a V-shaped cross section occupies increases, and the ratio of the bottom 170 occupies decreases. As a result, in the dark line 75, the area occupied by the bottom portion 170, which is unnecessary for focus determination, can be reduced, and the opening width E of the focus target groove 165 can be narrowed.

In the flow cell 2 of the embodiment described above, the focal target groove 65 forming the focal target 20 is formed on the surface 60A of the base plate 60, but the present invention is not limited to this. For example, as in the flow cell 202 shown in FIG. 7, the focal target groove 65 may be formed in the surface 61A of the cover plate 61 on the bonding side.

In the flow cell 2 of the embodiment described above, the focal target groove 65 is formed in the surface 60A of the base plate 60 by etching, but the present invention is not limited to this.
For example, like the flow cell 302 shown in FIG. , the pair of flow path forming plates 360B are bonded to the surface 360A1 of the bulk body 360A while being spaced apart by a distance corresponding to the width W of the flow path 16, so that the flow path 16 is formed on the surface of the base plate 360. There can be a mode of forming
In this case, the focal target grooves 65 can be provided on the surface of the base plate 360 by providing the focal target holes 365 penetrating from the front and back in each flow path forming plate 360B. This configuration has the advantage that the depth Da of the channel groove and the depth Db of the focal target groove in the base plate 360 are equal.

In the above-described embodiment, the side surfaces of the channel groove 63 are inclined so that the side surfaces have the functions of the side surfaces 71A and 71B of the focal target groove 65, and the side surfaces of the channel groove 63 are used as focal targets. may However, the focal target groove 65 is used in this case because the sides of the channel groove 63 do not produce dark lines 75 depending on the refractive index of the sample liquid flowing through the channel 16 .

In the above-described embodiment, the focus target 20 is formed with grooves, but the present invention is not limited to this. That is, the surface 60A of the base plate 60 or the surface 61 of the cover plate 61 on the joint side (that is, the joint surface between the base plate 60 and the cover plate 61) is marked by an appropriate marking method such as printing. Anything is fine. In this case, the thickness of the focal target 20 is very thin or flush with the surface 60A of the base plate 60 or the surface 61 of the cover plate 61 so as not to deform the cross-sectional shape of the channel 16. embedded in the

1 image analysis type particle analyzer 2, 202, 302 flow cell 4 sample liquid supply mechanism 6A light source device 8 camera 10 focus mechanism 12 computer 16 channel 20, 120 focus target 34 measurement light 38 telecentric microscope 40 telecentric lens 42 lens driving mechanism 46 Photographed image 50 Autofocus adjustment unit 52 Photographed image analysis unit 54 Camera control unit 60, 360 Base plate 61 Cover plate 63 Flow channel 63A Opening end face of flow channel 65, 165 Focus target groove 65A Opening end face of focus target 68 air passage 70, 170 focal target groove bottom 71A, 71B, 171A, 171B focal target groove side 75 dark line 360A bulk body 360B channel forming plate 365 focal target hole

Claims (3)

a flow cell in which a sample liquid flow channel in which sample particles are dispersed is provided;
a light source device that irradiates the flow path with measurement light;
A camera that captures the flow of the sample liquid in the flow cell,
In an image analysis type particle analyzer that analyzes the properties of the sample particles based on the image of the sample particles captured by the camera,
A focus adjustment unit that adjusts the focus of the camera,
The flow cell is
a base plate having flow channels on its surface;
a cover plate body joined to the surface of the base plate body in a surface contact state to close the flow channel groove to form the flow channel;
a focus target for focusing is provided on the surface of the base plate or the surface of the cover plate on the bonding side;
The focus adjustment unit
adjusting the focus of the camera based on the focus target ;
The focal target is
a focal target groove, which is a groove formed on the surface of the base plate or the surface of the cover plate on the bonding side;
the focal target groove has a side surface that slopes from the edge to the bottom of the open end face;
causing a dark line in a captured image of the focal target with the side surface;
The focus adjustment unit
adjusting the focus of the camera based on the locations of sharp spots and/or locations of blurred spots in the dark lines;
The flow cell is provided with an air passage communicating between the focal target groove and the outside.
An image analysis type particle analyzer characterized by: The focal target groove has a V-shaped cross section,
The image analysis type particle analyzer according to claim 1 , characterized in that: The focus adjustment unit
Based on the dark line and the depth from the opening end face of the flow channel groove, the focus of the camera is set from the opening end face of the flow channel groove in the depth direction of the flow channel groove to the depth of the flow groove. 3. The image analysis type particle analyzer according to claim 1 or 2 , wherein the image analysis type particle analyzer is adjusted to a position that is moved halfway from the position.

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